Passive Keyless Entry System (PKES) refers to a communication between a vehicle and a smart key according to the low-frequency signals and/or the high-frequency signals so as to achieve opening the door of the vehicle.
The effective propagation distance of the low-frequency signals can be 2-3 meters. Thus, the signals are only effective when the user is very close to the vehicle. The smart key can receive the low-frequency signals, such that a verification process can be started. However, the low-frequency signals can be multiplied by a third party, such that the low-frequency signals can be propagated a greater distance. Thus, the vehicle can be easily stolen.